Abstract:Optimizing pectinase-assisted extraction of Portulaca oleracea.polysaccharides by response surface methodology with polysaccharides yield and DPPH free radical scavenging rate.Based on the single factor experiment，according to the design principle of Box-Behnken center combination，the three factors of pectinase dosage，enzymatic hydrolysis temperature and extraction time were selected.Three factors and three levels response surface method was used to optimize the extraction conditions of polysaccharides from fresh Portulaca oleracea.The results showed that the optimum conditions were as follows solid-liquid ratio 1 ∶20（g/mL），pectinase dosage 0.15 g/L，enzymatic hydrolysis temperature 39 ℃ and enzymatic hydrolysis time 2.0 h.Under these conditions，the yield of Portulaca oleracea polysaccharide was 4.22 g/kg，relative standard deviation（RSD）was 1.53%，which was in agreement with the theoretical predicted value（4.15 g/kg）.The relative error was 1.52%；the average clearance of DPPH free radical was 53.1%，RSD was 1.49%，and the relative error with the predicted value （54.4 %）was 2.39 %.It indicated that the optimization of enzymatic extraction of antioxidant components from Portulaca oleracea by response surface methodology was stable and feasible.